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CALGB 10101: Alemtuzumab did not improve 2-year PFS or survival in chronic lymphocytic leukemia

Lin TS. J Clin Oncol. 2010;doi:10.1200/JCO.2010.29.7978.

Final results from the phase 2 CALGB 10101 trial showed that consolidation therapy with alemtuzumab improved complete response rates and minimal residual disease negative rates in patients with chronic lymphocytic leukemia but failed to improve 2-year PFS or OS.

Between 2005 and 2006, 102 patients with CLL were assigned 25 mg/m² IV fludarabine on days 1 to 5 of each cycle, along with 50 mg/m² IV rituximab on day 1, 325 mg/m² on day 3 and 375 mg/m² on day 5 of the first cycle. That was followed by 375 mg/m² rituximab on the first day of cycles two through six. Fludarabine/rituximab treatment was repeated every 28 days for six cycles.

Fifty-eight patients also received the monoclonal anti-CD52 antibody alemtuzumab (Campath-1H, Genzyme). The mean delivered dose was 483 mg, and 29 patients received the full planned dose of 493 mg.

For the entire cohort, the objective response rate was 90%, complete response rate was 29% and partial response rate was 61%. According to flow cytometry, 15% of patients were minimal residual disease negative.

Among patients who received alemtuzumab, the objective response rate was 91%, complete response rate was 66% and partial response rate was 26%. Fifty percent of patients were minimal residual disease negative. More than 60% of patients who had partial response fludarabine/rituximab induction went on to have complete response after alemtuzumab consolidation.

After a median follow-up of 36 months, median PFS was 72% and OS was 86% at 2 years.

Two-year PFS for patients who did not undergo alemtuzumab consolidation was 68% compared with 76% for those who underwent consolidation (P=.35). Two-year OS was also similar between the two groups (88% vs. 84%). Additionally, researchers found no difference in PFS or OS among the 30 patients who had complete response after fludarabine/rituximab induction, whether or not they received alemtuzumab.

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